Accumulation of Natural Radionuclides and Their Chemical Analogues by Sorbus aucuparia L. and Its Biochemical Indicators in Response to Chronic Radium Contamination

Abstract The relevance of this work is determined by the increasing anthropogenic impact on the environment, including that associated with the spread of natural radionuclides. This work studies the accumulation of radionuclides (U, 226Ra, 210Pb, and 210Po) and their chemical analogues (Ba, Sr, and Pb) in different organs (leaves, branches, wood, and bark) of the common rowan (Sorbus aucuparia) growing in an area contaminated more than 60 years ago by radium mining waste, and the plant’s response to combined radiation and chemical stress is assessed. Specific patterns of element accumulation are identified. It is found that 226Ra, Ba, and Sr have the highest accumulation coefficients and are predominantly distributed in the bark and branches. 210Pb, 210Po, and stable lead have low accumulation coefficients and accumulate mainly in the branches of the rowan. The biophilicity of 210Po is higher, as is indicated by the ratios of specific activities 210Po/210Pb > 1 in all organs except wood, where the 210Po/210Pb ratio is close to unity. Uranium is characterized by the lowest accumulation coefficients. Its content in plants in the contaminated area is comparable to or lower than control values, with the highest radionuclide concentrations observed in bark and leaves. Despite the high level of soil contamination and pollutant accumulation, key biochemical parameters (total antioxidant activity and polyphenol content) remain stable, indicating the relative resistance of rowan to chronic contamination. The data are valuable for the development of bioindication strategies, the remediation of radioactively contaminated areas, and environmental risk assessment.